<!DOCTYPE html>
<meta charset=utf-8>
<meta name=viewport content=width=device-width,initial-scale=1>
<style>
  :root {
    height: 100%;
  }
  body {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100%;
    margin: 0;
  }
</style>
<h1>unknown manual</h1>
